calculating enthalpy of reaction\ncompound δh (kj/mol)\nc6h6 (g) 82.90\nco2 (g) -393.51\nh2o (g)…

calculating enthalpy of reaction\ncompound δh (kj/mol)\nc6h6 (g) 82.90\nco2 (g) -393.51\nh2o (g) -241.82\nwhat is the enthalpy of combustion when 1 mol c6h6 (g) completely reacts with oxygen? 2c6h6 (g) + 15o2 (g) → 12co2 (g) + 6h2o (g)\n-3109 kj/mol\n-6339 kj/mol
Answer
Explanation:
Step1: Recall the formula for enthalpy of reaction
$\Delta H_{rxn}=\sum n\Delta H_f(products)-\sum n\Delta H_f(reactants)$
Step2: Identify the coefficients and enthalpies of formation
For the reaction $2C_6H_6(g)+15O_2(g)\rightarrow12CO_2(g) + 6H_2O(g)$, $\Delta H_f(O_2(g)) = 0$ (standard state). For $C_6H_6(g)$, $\Delta H_f = 82.90\ kJ/mol$, for $CO_2(g)$, $\Delta H_f=-393.51\ kJ/mol$ and for $H_2O(g)$, $\Delta H_f = - 241.82\ kJ/mol$.
Step3: Calculate enthalpy of reaction for 2 moles of $C_6H_6$
$\Delta H_{rxn}=[12\times(-393.51)+6\times(-241.82)]-[2\times82.90 + 15\times0]$ $=[-4722.12-1450.92]-[165.8]$ $=-6173.04 - 165.8=-6338.84\ kJ$ for 2 moles of $C_6H_6$.
Step4: Calculate enthalpy of reaction for 1 mole of $C_6H_6$
$\Delta H=\frac{-6338.84}{2}=-3169.42\approx - 3169\ kJ/mol$
Answer:
$-3169\ kJ/mol$